Wheatcroft, L., Klingner, N., Heller, R. et al. (4 more authors) (2020) Visualization and chemical characterization of the cathode electrolyte interphase using He-ion microscopy and in situ time-of-flight secondary ion mass spectrometry. ACS Applied Energy Materials, 3 (9). pp. 8822-8832. ISSN 2574-0962
Abstract
Unstable cathode electrolyte interphase (CEI) formation increases degradation in high voltage Li-ion battery materials. Few techniques couple characterization of nano-scale CEI layers on the macroscale with in situ chemical characterization, and thus, information on how the underlying microstructure affects CEI formation is lost. Here, the process of CEI formation in a high voltage cathode material, LiCoPO4, has been investigated for the first time using helium ion microscopy (HIM) and in situ time-of-flight (ToF) secondary ion mass spectrometry (SIMS). The combination of HIM and Ne-ion ToF-SIMS has been used to correlate the cycle-dependent morphology of the CEI layer on LiCoPO4 with a local cathode microstructure, including position, thickness, and chemistry. HIM imaging identified partial dissolution of the CEI layer on discharge resulting in in-homogenous CEI coverage on larger LiCoPO4 agglomerates. Ne-ion ToF-SIMS characterization identified oxyfluorophosphates from HF attack by the electrolyte and a Li-rich surface region. Variable thickness of the CEI layer coupled with inactive Li on the surface of LiCoPO4 electrodes contributes to severe degradation over the course of 10 cycles. The HIM–SIMS technique has potential to further investigate the effect of microstructures on CEI formation in cathode materials or solid electrolyte interphase formation in anodes, thus aiding future electrode development.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Copyright © 2020 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License (https://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html), which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. |
Keywords: | lithium ion batteries; SEI/CEI layer; helium ion microscopy; ToF-SIMS; surface degradation imaging and chemical characterization |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield) |
Funding Information: | Funder Grant number Engineering and Physical Sciences Research Council EP/L016818/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 09 Nov 2020 11:35 |
Last Modified: | 09 Nov 2020 11:43 |
Status: | Published |
Publisher: | American Chemical Society (ACS) |
Refereed: | Yes |
Identification Number: | 10.1021/acsaem.0c01333 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:167744 |